1. Field of the Invention
This invention relates to flow control valves and, more specifically, to gas flow reversing valves used in air conditioners and heat pumps.
2. Description of the Prior Art
The use of valves to control the flow of gaseous refrigerant between a compressor and two heat exchangers in refrigeration systems or heat pumps is well known. In general, it is desired to connect the discharge side of the compressor with a first heat exchanger, which may serve as an evaporator or as a condenser. The first exchanger is connected to a second exchanger, the outlet of which is connected to the suction side of the compressor. An expansion device is usually interposed between the exchangers.
Either exchanger may serve as a condenser or as an evaporator. It may be desirable to periodically reverse the flow of refrigerant through the exchangers, so as to defrost the evaporator, for example. This may be accomplished by means of a reversing valve which shifts positions so as to allow the discharge side of the compressor to communicate with the second heat exchanger rather than with the first exchanger, thereby directing the flow of gas from the discharge of the compressor to the second exchanger. This shifting of the valve also connects the suction side of the compressor with the first exchanger, thereby reversing the flow of gas through the system and reversing the function of each exchanger.
Examples of the general type of reversing valve described above are shown in U.S. Pat. Nos. 3,976,701 (Greenawalt) and 3,369,790 (McHale).
Both Greenawalt and McHale disclose a pilot-operated reversing valve. In each patent, the valve member, located inside a valve body, is shifted by means of pistons. Gas pressure is applied to move the pistons by means of solenoid-activated pilot valves and pilot lines.
Previous reversing valves had a substantial number of restrictions within the valve body itself, causing lower efficiencies than could otherwise have been obtained. Efficiency was also hindered due to the friction caused by the sliding motion of the valve member. Also, earlier designs required independent means to provide adequate sealing of the valve member against the valve body.